1. Field of the Invention
This invention relates generally to energy saving devices and more particularly to energy saving devices designed to preserve the refrigerated air within a refrigeration appliance.
2. Description of the Prior Art
Refrigeration appliances, such as refrigerators, freezers and ice chests, are useful and convenient machines for prolonging the usable lifetime of foodstuffs and other perishables. In fact, the common upright-type refrigerator found in virtually every household is considered to be almost a necessity by most persons living in today's society.
A problem with upright refrigerators (as well as freezers and iceboxes) is that when the door of the refrigerator is opened the cold, heavy air within the refrigerator quickly flows out and disperses into the ambient environment. In view of the fact that an average household refrigerator is opened many times during a typical day, the amount of cold air "spillage" can be quite significant. Since it takes energy to replace the cold air that was lost, it will be appreciated that cold air "spillage" is quite wasteful of both energy and money.
A design for refrigeration appliances that minimizes cold air spillage is the well known chest-style refrigeration appliance. The chest design or style of refrigeration appliance basically includes a rectangular, box-like container within which perishables are stored and a lid for closing the open top of the container. Since refrigerated air is denser and therefore heavier than room temperature air, it will not flow out of the container of the chest-style refrigeration appliance when the lid is opened.
A problem with chest-style refrigeration appliances is that it is more difficult to store and retrieve perishables or other contents from them than from upright refrigeration appliances. Furthermore, upright appliances require less floor space than chest-type refrigeration appliances of the same storage capacity, and thus are preferred in most applications where floor space is at a premium.
One possible solution to the cold air spillage problem of upright refrigerators and freezers is described in U.S. Pat. No. 3,241,899 of W. R. Donker which discloses a flexible curtain of material that can be stretched across the access opening of a refrigeration appliance. A limitation of Donker's invention is that it is meant to be used only at night when frequent access to the contents stored within the appliance is not anticipated. As such, the curtain is not readily removable and replaceable many times during a day, as would be the case with a home refrigerator or freezer.
T. Chovanec discloses in U.S. Pat. No. 2,610,473 an energy saving refrigerator display cabinet including a cylindrical body portion surrounding a series of spaced apart, rotatable shelves. The body portion of the refrigerator is equipped with a door which allows access to particular ones of the shelves after a refrigerated item is rotated into position in front of the door.
Apparent problems with Chovanec's invention include that it is mechanically quite complex and furthermore appears to be relatively inconvenient to use. The necessity for a motor to rotate the shelves so that refrigerated items are positioned in front of the door adds to the expense of the appliance and the fact that the shelves rotate would tend to introduce spillage problems.
There are numerous inventions found in the prior art for closing off portions of an upright refrigerator with the intention of inhibiting cold air spillage including those inventions disclosed in U.S. Pat. Nos. 1,630,160; 1,698,509; 1,748,670; 2,062,856; 2,124,857; 2,127,379; 2,266,857; 2,304,465; 2,381,598; 2,614,021 and 2,676,864. All of the above mentioned devices are relatively complex and therefore costly and prone to mechanical failure.